Method of manufacturing branched fittings

ABSTRACT

The invention relates to manufacturing of T&#39;&#39;s, crosses and like fittings, particularly those intended for operation at elevated pressures and temperatures. The method involves the use of three pairs of dies effecting compressing and upsetting of a tubular stock, whereby it becomes possible to treat a stock having the ratio of its wall thickness to the internal diameter in excess of 0.15 to 1.

United States Patent 1191 Moshnin et al.

[4 1 Feb. 25, 1975 METHOD OF MANUFACTURING BRANCHED FITTINGS [76] Inventors: Evgeny Nikolaevich Moshnin,

Ulitsa Akademika Pavlova, 50, kv. 5, Moscow; Nikolai lvanovich Romashko, Leninsky raion, selo Molokovo, Moskovskaya Oblast; Vladimir Zakharovich Gurevich, Yasny proezd, 4, korpus l, kv. 20, Moscow; Nikolai Stepanovich Voronov, ulitsa B. Khmelnitskogo, 68, kv. l8; Viktor Ilich Deryabkin, ulitsa B. Khmelnitskogo, 79, kv. 65, both of Belgorod, all of U.S.S.R.

[22] Filed: June 21, 1973 [2]] App]. No.: 372,415

52] us. (:1. 72/367, 29/157 T [51] Int. Cl B21k 21/00 [58] Field of Search 72/367, 370; 29/157 R, 29/157 T [56] References Cited UNITED STATES PATENTS 2,290,965 7/1942 Hodapp et al. 29/157 11/1956 Beatty 29/157 4/1957 Mark] 29/157 FOREIGN PATENTS OR APPLICATIONS 7,472 3/l902 Great Britain 29/l57 Primary ExaminerLowell A. Larson Attorney, Agent, or Firm-Eric H. Waters [57] ABSTRACT The invention relates to manufacturing of TS, crosses and like fittings, particularly those intended for operation at elevated pressures and temperatures.

3 Claims, 15 Drawing Figures PATENTEDFEB25I975 SHEET 1 OF 2 :5 fut Q an *7 Q, 1%

MGR w S METHOD OF MANUFACTURING BRANCI-IED FITTINGS The present invention relates to manufacturing of branched fittings, such as Ts, crosses and the like.

The present invention can be employed to utmost advantage in manufacturing of fittings which are meant to withstand in their furture use the action of elevated pressure and temperatures. In the case of such fittings, it is essential that the metal should be adequately strong over the entire body of a fitting and there should be a smooth junction or crotch between the main body of the fitting and its branch outlet.

This aim is attained in a best way by employing a pair of coacting dies having cylindrical recesses. A tubular stock oval in cross-section is compressed in these dies in the direction of the major axis of the oval.

One of these two dies has in the central portion thereof an opening extending transversely in respect of the longitudinal axis of the recess, while the stock should have made therein an aperture that should be positioned strictly in opposition to the center of this opening in the die. There is introduced through this aperture into the internal bore of the stock, prior to closing of the dies, a rod which is subsequently to carry thereon an additional die. As the two main dies are being closed, this additional die is drawn from the internal space of the stock. Thus, there is effected, simultaneously with compression of the stock in the radial directions, relative to its longitudinal axis, the shaping of the branch outlet (see, for example, US. Pat. No. 2,787,050, Cl. 29-157, 1947).

lt is to be understood that the thicker is the wall of the fitting to be manufactured, the greater effort should be applied to the rod carrying thereon the additional drawing die. As the size of the aperture in the wall of the stock cannot be considerably large (since the enlargement of this size substantially reduces the length of the branch outlet produced), the known method can find but limited application.

There is also known a method of forming a branch outlet of a fitting by upsetting a tubular stock by dies moving longitudinally of this stock. During this treatment not only does the stock get strengthened, but the thickness of the walls thereof is increased, which is quite essential. However, this method involves the use of a specific composition die, with one of the upsetting dies being introduced into the space inside this composition die. The latter has a lateral opening, which is used in the forming of a branch outlet. In operation the die is subjected to a considerable outwardly directed load (see, for example, Austrian Pat. No. 283,086, Cl. 49d; 39, 1970).

It is quite understandable that the thicker is the wall of the fitting, the thicker the walls of the composite die should be, so that their thickness attains such a value that the method itself becomes economically undesirable. Furthermore, the last-mentioned method, like the method described in the first instance, is not free from difficulties arising from. the use of an additional die secured on the rod extending through the aperture in the wall of the stock and through the opening in the die.

It is the main object of the present invention to create a method of manufacturing branched fitting, which, although possessing the advantages offered by the two above-specified methods, should provide, however, for forming relatively thick-walled fittings, owing to a new combination of the operations connected with plastic deformation of metal.

This new method, like the first one of the abovespecified known methods, also involves compression of a tubular stock in radial directions relative to the longitudinal axis of the stock by a pair of mutually complementary dies having recesses of substantially cylindrical shape, one of these dies having in the central portion thereof an opening which is employed for forming in the stock a bulge of a circular cross-section, in the place where the branch outlet should be. However, unlike this known method, in the new method the abovesaid compressing operation is followed by an operation of upsetting the stock with another pair of dies closing upon each other longitudinally of the stock, whereby the stock acquires the shape ofa barrel, while the bulge thereof becomes oval in cross-section. Thereafter the stock is once again compressed in radial directions relative to its longitudinal axis with a successive pair of coacting dies having recesses of substantially cylindrical shape, the two dies being complementary to each other, said dies being closed in the direction of the axis of said oval, each one of these two last-mentioned dies having an additional recess substantially of a cylindrical shape, complementary to the recess in the other die and extending transversely in respect of the main recess in the die, these additional recesses being intended for final formation of the branch outlet of the fitting from the said bulge.

With this sequence of operations the compressing and upsetting efforts are relatively small, the branch outlet becomes adequately long, while the wall thickness along the entire length thereof is considerably increased.

Moreover, the necessity of employing a die of a specific structure for upsetting the stock is eliminated.

According to a preferred embodiment of the present invention, it is advisable, upon having discontinued the compression in the last-mentioned pair of dies, to remove the apex of the branch formed, prior to making of the bore. It is quite understandable that the herein disclosed process is characterized by relatively moderate consumption of labour, while the tooling used in of a relatively simple structure. If the branch is to be relatively long, an aperture should be made in the side wall of the tubular stock prior to placing of the stock in the first pair of dies, and an additional drawing die is placed within the stock, to be connected to a rod extending through this aperture in the stock and through the opening in the corresponding die of the first pair.

In this case, simultaneously with compresion of the stock in radial directions relative to its longitudinal axis, the additional die is drawn by this rod from the tubular stock, in which way there is formed a bulge with an aperture, having an external diameter in excess of the external diameter of the fitting. In the course of the subsequent operations this bulge is reconstructed into its final form.

It is an important advantage of the present invention that it provides for manufacturing branched fittings from tubular stock having the ratio of the thickness of the wall to the internal diameter in excess of 0.15 l, as well as for forming a branch outlet without undue thinning of its wall.

Given hereinbelow is a detailed description of an embodiment of the herein disclosed method in accordance with the present invention, with reference being had to the accompanying drawings, wherein:

FIG. I is a cross-sectional view of the first pair of compressing dies and a tubular stock in the initial position for the first compressing operation;

FIG. 2 is a sectional view along line Il-II of FIG. 1;

FIG. 3 is a cross-sectional view of the first pair of compressing dies, upon their having closed;

FIG. 4 is a longitudinally sectional view of the second pair of dies and the tubular stock deformed into a stock with a lateral bulge, in the initial position for the upsetting operation;

FIG. 5 is a longitudinally sectional view of the second pair of dies at the end of their working stroke;

FIG. 6 is a cross-sectional view of the third pair of dies positioned to take part in the second compressing operation and the tubular stock deformed by the previous upsetting operation;

FIG. 7 is a view along arrow line A in FIG. 6;

FIG. 8 is a longitudinally sectional view of the third pair of dies, closed after the second compressing operation;

FIG. 9 is a cross-sectional view of the first pair of dies, ready to perform the first compressing operation, an additional die and a tubular stock in the initial position, according to the second embodiment of the present invention;

FIG. 10 is a sectional view along line X-X in FIG.

FIG. 11 is a cross-sectional view of the first pair of compressing dies after their having closed, the additional die having been drawn from the tubular stock;

FIGS. 12 to 15 illustrate the positions of the second and third pairs of dies and the successive shapes acquired by the tubular stock at the successive stages of the manufacturing process according to the second embodiment of the invention.

According to the first embodiment of the method in accordance with the present invention, there is used a metal tubular stock 1 (FIGS. 1 and 2), preferably a seamless tube, wherein the ratio of the wall thickness to the diameter is either equal to or in excess of 0.15

to I.

The external diameter of the stock may be in excess of the external diameter of the fitting to be manufacture by 10 to 15 percent.

The stock 1 is placed onto the bottom die 2 having in its top surface a recess 3 ofa semi-cylindrical shape, so that the longitudinal axis of the stock extends parallel to the longitudinal axis of the recess 3.

The upper die 4 has in the lower surface thereofa recess 5 also of a semi-cylindrical shape, with a cylindrical opening 6 intersecting this recess in the central part of the latter, the walls of this opening smoothly merging with the walls of the recess 5. The respective recesses 3 and 5 in these dies 2 and 4 are of a complementary shape.

First, the tubular stock 1 is subjected to compression in radial directions relative to its longitudinal axis. This is effected by closing the upper die 4 upon the bottom die 2, the curvature of the wall of the opening 6 in cross-section, as well as the curvature of the two coacting recesses 3 and 5 of the dies 2 and 4, also in crosssection, being in excess of the curvature of the external surface of the tubular stock I. As a result, the tubular stock 1 is contracted in transverse directions with the exception of the portion of the stock, which is opposite to the opening 6 in the upper die 4. This last-mentioned portion is deformed into a lateral bulge 7 (FIG. 3) which is circular in cross-section. Following the compression, the stock 1 is deformed into a stock la which is removed from the dies 2 and 4 that have performed the first compressing operation and is placed onto the bottom die 8 (FIG. 4) of the next pair of coacting dies 8 and 9 having flat working surfaces. With the upper die 9 being driven down the stock becomes upset, the bulge 7 becomes longer, and the stock la is deformed into a stock lb different from the stock la in that it has a barrel-like shape with greater dimensions of the central portion and a thicker wall, but is of a smaller axial length. The bulge 7 is likewise deformed into a bulge 7a oval in cross-section, the major axis ofthe oval being parallel to the axis of the tubular blank lb.

The thus deformed tubular blank lb is subsequently placed onto a bottom die 10 (FIGS. 6 and 7) having a recess 11 of a semi-cylindrical shape, so that the longitudinal axis of the stock lb is parallel to that of the recess 11.

An upper die 12 is positioned above the bottom die 10 for cooperation therewith, the die 12 also having a semi-cylindrical recess 13 extending parallel to the recess 11. Transversely to these complementary recesses 11 and 13, respectively, in the dies 10 and 12 there are cut in these dies further semi-cylindrical respective recesses l4 and 15, likewise of a complementary shape, the curvature of all these recesses ll, l3, l4 and 15 in cross-section being greater than that of the respective cylindrical surfaces of the stock lb which these recesses engage during the second compressing operation to which the stock lb is subjected in radial directions in respect of its longitudinal axis, as well as of the longitudinal axis of the lateral bulge 7a. With the dies 10 and 12 being closed in the direction of the minor axis of the oval defined by the cross-section of the bulge 7a, the stock 1b is deformed into a stock 10 (FIG. 8) that is different from the previous shape in that it has even smaller transverse dimensions and a longer bulge 7b of which the cross-sectional size is that of the final branch outlet.

Following the second compressing operation the apex of the bulge 7b is cut off either by a mechanical tool or by a jet of hot gases, the tool (not shown in the drawings) being moved along the line BB.

It is quite understandable that, owing to the upsetting operation, the thickness of the wall of the branch may be quite considerable.

When performing a method in accordance with the present invention, it is essential to heat up the stock to a temperature at which the metal becomes yielding under the pressure applied thereto.

The abovedescribed embodiment of the present invention enables to produce a branch outlet having a length up to 22 to 25 percent of the external diameter of the main body of the fitting.

In accordance with the second embodiment of the present invention, longer branches can be produced with the use of an additional drawing die 16 (FIGS. 9 and 10) introduced into the internal space of the stock 1d which latter is different from the abovespecified stock 1 (FIGS. 1 and 2) in that it has in the upper portion of the wall thereof an aperture 17 through which and through the opening 6 in the upper die 4 of the first pair of main dies 2 and 4 there is introduced a rod 18. The additional die 16 is secured to this rod 18, and during the compression of the stock 1d this die 16 is drawn from the stock by the rod 18, whereby the stock Id is deformed into a stock 1e (FIG. 11) with a branch 7c having a relatively large aperture.

Then the stock le is deformed into a stock 1f by the second pair of main dies 8 and 9 (FIGS. 12 and 13), the external diameter of the branch 7d being reduced by l0 to 20 percent. Thereafter the stock is deformed into the final article 1g in the third pair of main dies and 12 (FIGS. 14 and 15). During this operation the branch 7d is deformed into a branch 7e having a diameter equal to that of the main body of the fitting.

It is easy to comprehend that the pre-formed branch obtained by simultaneous upsetting and drawing with the help of the dies 2, 4 and 16 becomes in the course of the subsequent treatment longer than the branch obtained by the first-described embodiment of the present invention, its final length being up to 28 to 30 percent of the external diameter of the main body of the fitting.

The invention does not prohibit the employment of dies having recesses of a shape somewhat different from purely cylindrical one, e.g., frustoconical recesses having a relatively small taper angle, or else recesses having both cylindrical and frustoconical portions with a relatively small taper angle.

What we claim is:

1. Method of manufacturing branched fittings from tubular metal stock, including the steps of compressing said stock in radial directions relative to its longitudinal axis with a first pair of cooperating dies having substantially cylindrical recesses of a complementary shape, one of said dies of said first pair having an opening intermediate the ends thereof for forming in said stock a bulge of a circular cross-sectional shape at the location of the branch outlet which is to be produced; subsequently upsetting said stock obtained through said compressing operation by a second pair of male dies driven towards each other longitudinally of said stock so as to impart to said stock a barrel-like shape and an oval cross-section to said bulge; and re-compressing said stock in radial directions relative to said longitudi nal axis thereof after subjecting said stock to said upsetting operation through a third pair of cooperating dies having recesses ofa substantially cylindrical shape, said recesses in said third pair of dies being complementary to each other, said dies of said third pair being closed in the direction of the minor axis of said oval, each die of said third pair having an additional recess of a substantially cylindrical shape, said additional recesses, respectively, of said dies of said third pair being complementary to each other and extending transversely in respect of said first-mentioned recesses in said respective dies of said third pair, said additional recesses being adapted to effect final formation of said fitting branch from said bulge.

2. A method according to claim 1, including removing the apex of said branch upon completion of said compressing operation in said third pair of dies so as to form an aperture in said branch.

3. A method according to claim 1, including drawing said branch by means of an additional die during the course of compressing in said first pair of dies, said tubular stock, provided in advance with an aperture in the wall thereof, being positioned so that said aperture is brought in opposition to said opening in one of said dies of said first pair of dies, introducing a rod through said aperture, securing said additional die to said rod within the internal space of said tubular stock, said additional die being drawn from said tubular stock by said rod, so as to produce said branch with an aperture.

=l l l l 

1. Method of manufacturing branched fittings from tubular metal stock, including the steps of compressing said stock in radial directions relative to its longitudinal axis with a first pair of cooperating dies having substantially cylindrical recesses of a complementary shape, one of said dies of said first pair having an opening intermediate the ends thereof for forming in said stock a bulge of a circular cross-sectional shape at the location of the branch outlet which is to be produced; subsequently upsetting said stock obtained through said compressing operation by a second pair of male dies driven towards each other longitudinally of said stock so as to impart to said stock a barrel-like shape and an oval cross-section to said bulge; and re-compressing said stock in radial directions relative to said longitudinal axis thereof after subjecting said stock to said upsetting operation through a third pair of cooperating dies having recesses of a substantially cylindrical shape, said recesses in said third pair of dies being complementary to each other, said dies of said third pair being closed in the direction of the minor axis of said oval, each die of said third pair having an additional recess of a substantially cylindrical shape, said additional recesses, respectively, of said dies of said third pair being complementary to each other and extending transversely in respect of said first-mentioned recesses in said respective dies of said third pair, said additional recesses being adapted to effect final formation of said fitting branch from said bulge.
 2. A method according to claim 1, including removing the apex of said branch upon completion of said compressing operation in said third pair of dies so as to form an aperture in said branch.
 3. A method according to claim 1, including drawing said branch by means of an additional die during the course of compressing in said first pair of dies, said tubular stock, provided in advance with an aperture in the wall thereof, being positioned so that said aperture is brought in opposition to said opening in one of said dies of said first pair of dies, introducing a rod through said aperture, securing said additional die to said rod within the internal space of said tubular stock, said additional die being drawn from said tubular stock by said rod, so as to produce said branch with an aperture. 